Such devices are known and are for example used to assist a driver to park its car by informing said driver of the vicinity of obstacles surrounding the vehicle. Generally, such a sensor device informs the driver of the presence of obstacles around the vehicle during driving.
A typical single pad capacitive sensor device works by putting charge onto a sensor pad and measuring the change in voltage caused by the presence of an object in the detection area. The presence of an object changes the coupling capacitance of the sensor pad to the environment. Using nearby plates that are driven from amplifiers following the input signal with a gain near one is the well known guard principle for eliminating some parasitic capacitances i.e. straightening the field toward the target. The measured object volume can be effectively moved by using other nearby plates that are driven from amplifiers following the input signal with different gains. However, this is not a practical solution in many cases as driving nearby plates from a guard amplifier following the signal on the sensor pad but with a gain greater than one can easily cause the system to oscillate.